1. Field of Invention
The present invention relates to increasing the number of communication channels, or information per fixed frequency bandwidth. In particular, it relates to a systematic method of increasing the number of channels per fixed frequency bandwidth significantly reducing each individual channel's bandwidth by using a reduced bandwidth Frequency Modulation or Phase Modulation signal.
2. Related Art
With each year, the MW, SW, VHF, and UHF bands have become more congested with increased demands from cell phones, personal communications devices, and pagers. However, the available radio frequency bandwidths in the MW, SW, VHF, and UHF bands available to the communications user has not expanded due to regulations and restrictions imposed by governmental and international treaty restrictions. The present day communication bands are essentially filled to capacity using present day modulation techniques and channel spacing. With the growing demands for communications systems, there is increased competition for already crowded radio frequency bands.
In the past, manufacturers have moved to higher frequencies to find additional or available communications channel bandwidth. Further, in most industrialized countries, all of the economically viable radio frequencies are committed to specified communications channels and their corresponding spacing. Seeking higher frequencies also poses significant health problems that are known to exist at higher frequencies from radiated radio frequency energy.
The only solution to the congested communications radio spectrum is to increase the number of communication channels in each allotted radio frequency band. The obvious methodology is to use communications channel bandwidth compression techniques. One problem with many of the communications systems that uses narrower bandwidths are a sacrifice of sound qualities and increased bit error rates in data channels. Many of the remaining communications channel compression schemes require complex and expensive electronic implementation.
Thus, there is a need for communications channel bandwidth reduction techniques to allow information to be transmitted over communications channels with reduced bandwidth, while retaining relatively high sound quality and lower bit error rate in data channels.